Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies

Abstract

Aims. We are searching for star formation regions in the hosts of potentially young radio galaxies (gigahertz peaked spectrum and compact steep spectrum sources). Methods. We used near-UV imaging with the Hubble Space Telescope Advanced Camera for Surveys. Results. We find near-UV light could be the product of recent star formation in five of the nine observed sources, though other explanations are not currently ruled out. An additional two sources show marginal detections. The UV luminosities of the GPS and CSS sources are similar to those of a sample of nearby large-scale radio galaxies. Stellar-population synthesis models are consistent with a burst of recent star formation occurring before the formation of the radio source. However, observations at other wavelengths and colors are needed to definitively establish the nature of the observed UV light. In the CSS source 1443+77, the near-UV light is aligned with and is co-spatial with the radio source. We suggest that the UV light in this source is produced by star formation triggered and/or enhanced by the radio source.